Decoder and decoding method for decoding a code by selecting a path out of paths in a trellis diagram
AssigneeFujitsu Limited
InventorsToshikazu Kanaoka, Toshihiko Morita
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Abstract
A decoder decodes a code by selecting, based on a predetermined condition, a path out of paths representing a transition of each of states in a trellis diagram. A storing unit stores, when a path at time k is selected, information on a selection history of a path selected at time prior to time (k−(a constraint length of a code)+1). A path detecting unit detects a path to be excluded from a path selection candidate, based on the information stored in the storing unit and information on a state of a transition source when a state transition occurs from time k−1 to time k.
Claims10
A decoder that decodes a code by selecting, based on a predetermined condition, a path out of paths representing a transition of each of a plurality of states in a trellis diagram, the decoder comprising:
- a storing unit that stores a value of a first bit of bits representing a state of a source of the transition in the trellis diagram as information on a selection history of a path selected before time (k−(a constraint length of a code)+1) by adding the value to path selection history information on paths selected by time k−1 when a path at time k is selected;
- a path detecting unit that detects a path to be excluded from a path selection candidate, based on the information stored in the storing unit and information on a state of a transition source when a state transition occurs between time k−1 and time k;
- and
- a decoding unit that decodes a code by deleting the path detected by the path detecting unit.
A method of decoding a code by selecting, based on a predetermined condition, a path out of paths representing a transition of each of a plurality of states in a trellis diagram, the method comprising:
- storing a value of a first bit of bits representing a state of a source of the transition in the trellis diagram as information on a selection history of a path selected before time (k−(a constraint length of a code)+1) by adding the value to path selection history information on paths selected by time k−1 when a path at time k is selected;
- detecting a path to be excluded from a path selection candidate, based on the information stored at the storing and information on a state of a transition source when a state transition occurs between time k−1 and time k;
- decoding a code by selecting the path detected by the detecting.
Dependencies are inferred from the claim text.